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Denver Water is planning a major expansion of the reservoir that will increase height of the Gross Reservoir Dam outside Boulder by 131 feet and water storage by 77,000 acre-feet. Local residents and environmental groups are fighting against the expansion. (Chris Schneider, Special to The Colorado Sun)

The Boulder County Commissioners on Tuesday unanimously approved a settlement allowing Denver Water to expand the dam and pool at Gross Reservoir, despite vocal opposition from some residents, after a $10 million mitigation deal was sweetened by $2.5 million to soften construction impacts for neighbors.

Denver Water is likely to vote Wednesday to approve a total of $12.5 million in mitigation and open space donations for Boulder County, after last-minute talks raised the sum. 

The commissioners said they were heartsick at the destruction the dam expansion will cause for neighbors and for revered county open lands. But, they added, county attorneys advised them that federal laws preempt their planning process because the existing dam includes a hydroelectric generator and is therefore controlled by federal laws.

The attorneys said Boulder County would lose a federal suit filed by Denver Water and that the agency would withdraw its mitigation offer if they delayed a vote. 

Denver Water already has the federal approval it needs to raise the dam on South Boulder Creek by 131 feet, and inundate the surrounding forest for 77,000 more acre-feet of storage, nearly tripling capacity. 

“This project is bad for the environment, and the mitigation being offered is not sufficient,” Commissioner Claire Levy said, adding that she believes the county did all it could to alter the project impacts. 

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“I understand people’s disappointment with where we are. The law is not on our side,” she added, and said she did not want county residents to “come up empty handed.” 

Boulder County should not be “bullied” by Denver Water, Levy said, and “now it’s up to them to do the right thing” by further mitigating the dam’s impacts. “All projects on this scale are simply obsolete.” 

The commissioners wanted Denver Water to go through the county’s existing “1041” land use process, allowed under state law, before construction on the Gross Reservoir expansion begins. But in July, Denver Water sued, saying federal laws superseded Boulder County’s process and that its federal permit required the utility to begin construction by 2022. Boulder County was intentionally slowing down the project, Denver Water argued. 

“I hate the position Denver Water” has put Boulder County in, commission chair Matt Jones said. “It’s 20th century thinking, it’s Hoover Dam thinking.” 

Jones said he believes Denver Water put a hydroelectric generator at the dam “so they could roll over Boulder County” by avoiding future county regulation when it came time to expand. Denver Water says the dam currently generates about 7.6 megawatts of electricity

In arguing for accepting the expanded $12.5 million settlement offer, Jones said, “It’s nothing, or this.” 

The commissioners said they’d been flooded by opposition to the settlement since it was announced last week. 

“I read all your emails. I hear you. I agree with most of what you are saying,” Jones said. Later, he added “It’s just not right.” 

A sign to stop the dam expansion in a neighborhood near Gross Reservoir outside Boulder on Monday, July 1, 2019. (Chris Schneider, Special to The Colorado Sun)

The Environmental Group, representing some Gross Reservoir neighbors and county residents, said it was “extremely disappointed in Boulder County’s decision, the process and the lack of public involvement. The county made the call and is 100% responsible for the outcome.”

Denver Water Manager Jim Lochhead said in a statement after the vote, “I appreciate that this was a hard and emotional decision for the Boulder County Commissioners.

“We have tried for the last year to go through the County’s 1041 land use process, and only after delays were we forced to file litigation to prevent violation of the order by FERC for us to commence construction of the project. Denver Water continues to be committed to do everything in our power to mitigate local impacts of construction,” Lochhead said.

Construction would impact surrounding forests, trails, roads and neighbors, and also temporarily cut off access to popular open spaces in parts of the area. Commissioner Marta Loachamin said she toured areas around Gross Reservoir for the first time in June, and was struck by markings in the forest showing how many trees will have to be removed and how high the new water pool will rise in the canyon. 

Conservation groups who have sued to stop the dam expansion can continue to negotiate with Denver Water for additional mitigation, deputy county attorney David Hughes told the commissioners. Denver Water has indicated they would continue to talk with the groups, he said. 

The conservation groups are adamant Boulder County could have negotiated for more mitigation. Save the Colorado and PLAN-Boulder County said they had proposed $70 million in mitigation as a settlement, and that Boulder County stopped including them in talks last week. 

The agreement with Denver Water now includes: 

  • $5 million for the construction impacts on immediate neighbors of the reservoir.
  • $5.1 million to Boulder County open space funding to acquire new land or repair and maintain trails and facilities under extra strain from visitors who can’t use Gross Reservoir spaces.
  • $1.5 million to mitigate greenhouse gas emissions from construction.
  • $1 million for South St. Vrain Creek restoration. 
  • A transfer of 70 acres of Denver Water land near Gross Reservoir to Boulder County to expand Walker Ranch Open Space.

Save the Colorado said it wanted at least $15 million more from Denver Water to mitigate the impacts in Grand County of taking more Fraser River water to fill an expanded Gross Reservoir. Many conservation groups say Front Range communities have damaged the Colorado River headwaters by transferring so much drinking water across the Continental Divide. 

This story was updated at 3:55 p.m. and 4:33 p.m., Nov. 2, 2021, with additional comments.

Michael Booth

Michael Booth is a Colorado Sun reporter covering health, health policy and the environment. Email: Twitter: @MBoothDenver